Pictured directly to the left is a cross-section of the the inside of a renal medulla (where filtration occurs). The small purple colored dots are the nuclei of the kidney’s epithelial cells which make up structures such as the walls of capillaries and microtubules. Because this is cross section the actual tubule is white space surrounded by a ring of cells, like looking at a pipe through the hole. The orange arrow is pointing at an epithelial cell that has been altered by the cytopathic effects of the BK Virus. It becomes enlarged and as you can see the tubule will begin to be closed up by the malformed cells, as well as the resulting scar-tissue.
In the picture to the right, cells with a BK nuclear intrusion are highlighted using SV40 immunostaining. SV40 (Simian virus 40) is a virus in the same family as the BK (polyoma viruses) that can infect both humans and simians alike. Using it to stain locations of BK intrusion is another example of how we rely on research animals to be better able to help and understand ourselves, much like with rATG and hATG (see rATG post).
The final image shows fluorescent tagged immunoglobulin which is concentrated around areas of what is thought to be BK virus cytopathic manifestation.
So, is the virus dangerous because it forms many of these little scar tissue clumps (shown in the pictures), and that prevents the kidney from filtering blood effectively? Could this, if it is the case, also contribute to kidney failure in the elderly?
ReplyDeleteIn short yes. The virus affects kidney function by causing inflammation to occur and scar tissue to form which can effectively bring blood filtration to a grinding halt. Kidney failure in the elderly, however, is mostly attributed to a combination of high blood pressure and an increase in fatty deposits on the inner linings of arteries. These two factors coupled with the fact that arterial strength and elasticity decreases with age reduce the blood supply to the kidney while simultaneously harming the glomeruli which filter the blood.
DeleteAs an aside, are there things that can be done just to address the inflammation?
ReplyDeleteUnfortunately, the inflammation of the cells is due to the cytopathic effects of the BK virus and occurs on the level of individual affected cells. This means that really the only effective way of reducing it is to stop the proliferation of the BK virus. Inflammation here can be seen as less of a severe symptom and more as a marker of what is to come.
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